More Co2, less light. Spot treat with Seachem Excel, EasyCarbo or H2O2, and physically remove algae if possible.
I found on ebay SEACHEM Flourish Excel - 500ml.
http://cgi.ebay.com/SEACHEM-Flouris...UK_Pet_Supplies_Fish&hash=item1c10dda085#shId
Is this one fine?